Last week on January 20, 2011, the FDA’s Peripheral and Central Nervous System Drugs Advisory Committee decided not to recommend approval of Lilly’s Amyvid™ (florbetapir) in a 13:3 vote. Florbetapir is an imaging agent used with Positron Emission Tomography (PET) to show accumulation of beta-amyloid plaque in the brain. I previously wrote about Lilly’s acquisition of Avid Radiopharmaceuticals for florbetapir on this blog.
This imaging approach aids in the early detection of Alzheimer’s disease, as a negative scan, not showing any beta-amyloid plaque, would rule out Alzheimer’s disease. Given that it is currently, hard to distinguish age related memory less and different types of dementia, diagnostic imaging tools have an important role to play.
The FDA advisory committee’s decision would probably have come as a surprise to Lilly, since the clinical trial data showed clear efficacy and no safety concerns. While the committee rejected immediate approval, they did recommend approval (16:0), conditional on a training program to show that radiologists and readers of the scans could be accurate and consistent in their image interpretation. The FDA is not bound by the Committee’s recommendations but is required to take them into consideration when deciding whether to grant approval.
Imaging is becoming increasingly important in clinical trial design. In therapeutic areas such as osteoporosis, rheumatoid arthritis and oncology, imaging end points are often surrogates for drug efficacy.
The challenge that emerging biotechnology companies face in linking imaging to drug use, is the variability of readers outside a controlled clinical trial environment where images may be read centrally. Standardization of image acquisition and reading needs to take place, so that a radiologist in different hospitals can come up with the same findings. Those involved with imaging clinical trials know how hard this can be, even within the controlled clinical trial setting.
The recommendation of the FDA advisory committee that Lilly needs to put in place a training program to show accuracy and consistency of readers is a valid concern and one that all biotechnology companies and pharmaceutical companies should take note of when developing imaging agents.